钙质泥岩水岩作用特征及遇水软化机理

为掌握泥岩遇水后的工程特性,进一步揭示其遇水软化机理,对取自宁夏固原引水隧洞工程遇水易软化的白垩系钙质泥岩进行了矿物成分分析和物理力学性质试验.在此基础上,分析了钙质泥岩水岩作用特征,探讨了不同黏土矿物含量钙质泥岩遇水后强度和变形参数的变化规律和软化机理.研究结果表明:钙质泥岩的膨胀性及其强度遇水后迅速衰减;遇水后钙质泥岩力学参数的变化与黏土矿物含量均呈自然对数关系;钙质泥岩遇水软化是其在吸、失水过程中内部水化膨胀反应及其损伤不断加剧造成的,软化机理可用水岩作用过程示意图详细描述. 

Water-Rock Interaction Characteristics and Softening Mechanism of Calcareous Mudstone

In order to deeply research the softening mechanism of soft rock after interaction with water, cretaceous calcareous mudstone, water softening rock from a water diversion tunnel in Guyuan City, Ningxia Hui Autonomous Region, was investigated by the analysis of its mineral compositions and the test of its physical-mechanical properties. Based on the test results, the water-rock interaction characteristics of calcareous mudstone were analyzed, and variation rules of strength and deformation parameters with clay mineral content were discussed. The research results show that swelling and strength of calcareous mudstone decay rapidly after water invading. There exist natural logarithmic relationships between variations of mechanical parameters and clay mineral content. The water softening of calcareous mudstone is caused by the internal hydration swelling reaction of rock and its damage intensifying in the circulation process of water absorbing and water losing, and the softening mechanism can be described in details with the schematic diagram of water-rock interaction process.